Radical addition initiated by amino alcohols
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 9, September, 2006
1625
and the studied sample reduced to equal detection conditions.
The S values were determined using the authors´ program packꢀ
age and an automated system of data reception. The samples
contained the initiator (0.1 mol L–1) and MNP (0.1 mol L–1) in
a solution of CCl4. Absorption spectra were recorded on
a Shimadzu UVꢀ320 instrument in the wavelength region
from 200 to 800 nm. Samples were placed in a cell with a
Teflon valve, and the mixture was liberated from dissolved gases
in the same way as when preparing samples for ESR measureꢀ
ments.
Kinetic parameters were determined by the method of initial
rates. It has preliminarily been shown that in the chosen condiꢀ
tion range the kinetic curves had no inflections and no induction
period was observed. To determine the reaction orders, the conꢀ
centrations of the initiators and olefin were varied in the ranges
0.005—0.02 and 0.6—1.5 mol L–1, respectively.
traps was used. The trap was MNP, which interacts with
radicals to form spinꢀadducts 7
But—N=O + R• → But—N(O•)—R.
7
The formation of several spinꢀadducts was observed in
all systems containing the initiator, CCl4, and MNP. The
initiator appears in the spectrum as a triplet with the HFC
constant on the nitrogen nuclei aN = 14.0 G, which corꢀ
responds to the parameters of the spinꢀadduct of the
tertꢀbutyl radical with the trap6 formed due to the partial
photolysis of the trap
But—N=O
But•
But2N—O•.
The second spinꢀadduct appears in the spectrum
(Fig. 1, a) as a triplet of multiplets characterized by the
triplet splitting constant aN = 11.9 G and the multiplet
splitting constant a = 2.3 G. The values of the splitting
constants coincide with the constants of the spinꢀadducts
of the •CCl3 radicals with the trap.6 Storage of the samples
containing amines and amino alcohols at room temperaꢀ
ture results in a change in the spectra and the appearance
of a triplet with the constant aN = 12 G (Fig. 1, b).
Probably, the spinꢀadducts with the structure
Results and Discussion
The reaction of CCl4 with octꢀ1ꢀene in the presence
of aromatic amino alcohols occurs mainly to form the
addition product: 1,1,1,3ꢀtetrachlorononane (6).
CCl4 + H2C=CH(CH2)5Me → CCl3CH2CH(Cl)(CH2)5Me
6
In addition to compound 6, hexachloroethane and the
product of allylic substitution 3ꢀchlorooctꢀ1ꢀene were
found in insignificant amounts (at most 1—2%), as well
as telomers that were not determined by GLC. Their total
yield did not exceed 1%. The selectivity value was deterꢀ
mined as the ratio of the yield of compound 6 to the total
conversion of octꢀ1ꢀene. At the initial concentration of
olefin 0.64 mol L–1 and a concentration of amino alcoꢀ
hol 1 of 0.015 mol L–1, the reaction ceases in ~1 h (olefin
conversion 37%). In the case of amino alcohol 2 under
similar conditions, the reaction ceases in ~2 h (olefin
conversion 34%), which is related to the consumption of
the initiators. The reaction order was determined only
from the initiator and olefin, because CCl4 was used in
more than twofold excess over olefin and a decrease in
this ratio strongly changes the selectivity of the reaction:
the yield of telomers increases multiply.
formed from trichloromethylꢀtertꢀbutyl
nitroxide correspond to this parameter.7
As can be seen from the data in Fig. 2, the kinetic
curves of accumulation of the spinꢀadducts of the trap
with the radical formed due to the reaction of the initiator
with CCl4 pass through a maximum or reach saturation. A
decrease in the concentration of the spinꢀadducts is reꢀ
lated to the consumption of the trap and adduct due to
side reactions. The maximum concentrations of the spinꢀ
adducts with the trap and the initial rates of octene conꢀ
version referred to the initiator concentration are preꢀ
sented in Table 1. It is seen that the initiator activity
correlates with the maximum concentration of the spinꢀ
adducts.
We detected the spinꢀadduct that appears in the specꢀ
trum as a triplet of doublets (Fig. 3) in addition to the
mentioned spinꢀadducts in the system containing comꢀ
pound 3. Its hyperfine triplet splitting constant on the
nitrogen atom is aN = 16.4 G, and the doublet splitting
constant is а = 3.0 G. In this case, doublet splitting is the
splitting on the hydrogen atom.
In excess CCl4 the rate equation has the form
r = d[C8H16]/dt = keff[AA],
where AA is amino alcohol.
The zero order with respect to olefin indicates indiꢀ
rectly the radical mechanism of the reaction.4,5 If the
reaction proceeds via the coordination radical mechaꢀ
nism, the olefin concentration should enter into the kiꢀ
netic equation. In this case, the kinetics is usually deꢀ
scribed by the first order with respect to olefin.
The order of the HFC triplet conꢀ
stant indicates that the radical inꢀ
teracting with the trap increases
the electron density on the nitroꢀ
To reveal the nature of active species involved in the
reaction, the ESR method with the technique of spin
gen atom. Therefore, the radical
contains a donor group, for inꢀ